"Other straps might include a sword harness, but on the whole it's a rather enigmatic item," she said.

Experts said the ring's "dark red gem" is most likely to be a garnet

A 22mm (0.9in) diameter medieval gold finger ring featuring a gem, found using a metal detector near Bury St Edmunds, was also declared treasure.

Andrew Brown, finds recording officer at Suffolk County Council, said: "Gold isn't hugely common in any period, but if you own an object of more value in this period it's like to be a finger ring, but we can't tell if it belonged to a man or a woman.

"We'd expect this to have belonged to a wealthier family, but just how wealthy is difficult to gauge from this single item."